March 31, 2020
Hand hygiene has an important role in preventing the spread of a wide range of pathogens, most especially in healthcare settings. With the outbreak of the coronavirus disease, soaps and sanitizers are flying off the shelves and leading to supply disruptions in many areas across the United States and the whole world. But not all sanitizers will be equally effective against the coronavirus.
Skin on the hands and fingers is uneven, bumpy, and full of ridges, no matter how smoot it may feel. Those miniscule ridges are perfect for nanoparticle-sized viruses to latch on and get lodged in until transferred to more vulnerable cells in the nose, mouth, or eyes. This is why vigorous hand-washing and sanitizer are so important, as is avoiding touching the face as much as possible.
Many viruses, including the novel coronavirus, are a self-assembled nanoparticle. The virus commonly gets transferred from the hands and enters the body through the nose, mouth, or eyes where it attaches to vulnerable cells. Basically, the membrane of the virus fuses with the membrane of the cell. From there it releases genetic material called RNA and hijacks the cell and starts replicating and spreading.
The outer lipid bilayer (made up of spike proteins, envelope proteins, and membrane proteins) is the weakest part of the virus. Soap contains fat-like compounds called amphiphiles. They are similar to the lipids on the virus membrane and bind with them, causing them to disconnect. Once the lipid layer dissolves it mechanically forces the virus disengage from the skin and also causes the virus to fall apart. Hence the reason the Centers for Disease Control and Prevention (CDC) recommends washing hands with plain soap and warm water for 20 seconds as the best way to mechanically remove pathogens. It decreases the risk of getting sick and helps prevent the spread of infections.
Alcohol is another long-known disinfectant and has been used for disinfecting hands since the 1880’s. The right alcohol content effectively dissolves the lipid membrane and the virus. This is why hand antiseptics often include a high percentage of ethanol, isopropanol, N-propanol, or a combination of these products. But these products are only effective with the right concentrations of alcohol.
When you are unable to wash with soap and water, the CDC recommends alcohol-based hand sanitizers with a minimum of 60% ethanol or 70% isopropanol. For healthcare settings the CDC recommends alcohol-based hand sanitizers with more than 60% ethanol or 70% isopropanol. Hand sanitizers with less alcohol content will be less effective and will not remove all types of germs. And coughing or sneezing into hands requires more than sanitizer. This is because sanitizer will not work as effectively against mucous, which helps protect the microbes. This is why the first choice should be hand washing, with sanitizers acting as a practical alternative when soap and water are not available.
According to the FDA and the CDC, consumers should not attempt to make their own sanitizer. Not only can it be ineffective, but homemade hand sanitizer can lead to skin burns if made incorrectly. To help boost the supply and protect public health, the U.S. Food and Drug Administration (FDA) has updated guidance documents for the preparation and compounding of certain alcohol-based hand sanitizer products.